The present invention relates to a stable hard-boiled candy containing sucrose, hydrogenated starch hydrolysate (HSH), and optionally corn syrup. This novel candy product is characterized by having a high index of whiteness and improved stability which is identified by a reduced moisture absorption.
Boiled sweets, commonly called hard sweets or hard boiled candies (hereinafter “hard-boiled sweets”, “hard-boiled candies”, “boiled sweets”, or “candy”), are solid and essentially amorphous, i.e., glassy, confectionary products. They are obtained by extensive dehydration of carbohydrate syrups. Boiled sweets can be prepared using either or two methods: (1) casting or depositing; or (2) roping and stamping. Both of these techniques are well known in the art. Depositing is typically appropriate for syrups having a measured viscosity of less than 2,000 cps, while roping and stamping is suitable for syrups having higher viscosities. The principal market for boiled sweets currently consists of sugar products prepared from non-hydrogenated carbohydrate syrups.
Boiled sweets must be stable over time. They must have an adequate shelf-life which means that the appearance and mouth feel of the hard-boiled sweet varies as little as possible from the time when they are manufactured up to the time when they are consumed, so as to provide products which are visually attractive and also pleasant in the mouth. One major problem is that sugarless boiled sweets may become sticky during storage. Once wrapped, the stickiness makes it difficult or impossible to remove the wrapping materials before they are consumed. Alternatively, unwrapped boiled sweets may become bonded together or “caked” so that they cannot be easily separated. Another problem is that boiled sweets may become flowable and lose their shape during storage prior to consumption. Further, some or all of the components of the hard-boiled sweets can crystallize during storage and destroy the desired amorphous or glassy structure of the candy.
This problematic degradation towards a sticky and syrupy state due to moisture pickup or heat can be explained by surface phenomena and depth phenomena. The origin of surface phenomena is in the hygroscopic nature of boiled sweets. It is known that boiled sweets, which are essentially anhydrous products, have very low equilibrium relative humidities, substantially lower than the ambient relative humidities commonly found under normal storage conditions. This explains why an uptake of water necessarily occurs at the surface of the sweets as soon as they are exposed to air. When this water uptake is sufficiently high, it tends to liquify the surface of the sweets, which takes on the characteristics of a syrup and makes them sticky. The higher the water content of the boiled sweets, the quicker this phenomena occurs.
The depth phenomena have a thermal origin. When a boiled sweet is exposed to a temperature that is above the glass transition temperature (Tg) of the boiled sweet, the boiled sweet will become deformable and can even melt. To avoid the negative aspects of the depth phenomena, it is generally preferred that the storage temperature is below the glass transition temperature (Tg) of the boiled sweet. This preference is known in the art and is discussed in an article entitled “La transition vitreuse: incidences en technologic alimentaire” [Glass transition: incidents in food technology] by M. Le Meste and D. Simalos, published in I.A.A. of January/February (1990), which is hereby incorporated by reference. The glass transition temperature is the temperature at which, upon heating, a glassy and solid boiled sweet softens and eventually becomes a syrupy liquid. This temperature is normally measured by differential scanning calorimetry (DSC). However, it is also understood that a boiled sweet may be subject to a deformation, or even to a complete flow, when its storage temperature significantly exceeds its glass transition temperature. In such a case, the initially dry product becomes sticky. Furthermore, the higher the water content of the boiled sweet in question, the lower the glass transition temperature of the boiled sweet and the greater the risk of stickiness, deformation or flowing during the storage of the boiled sweet.
In addition to the stickiness and flow stability problems discussed above, boiled sweets have the tendency to crystallize in an uncontrolled manner during storage and thereby lose not only their very attractive glassy appearance but also their stability. The crystallization can occur either at the surface of the sweet or at the center of the sweet. The surface crystallization requires a significant water uptake. It also requires a sufficient concentration of crystallizable molecules in the liquefied peripheral layer. When these two conditions are met, crystallization is then observed which occurs from the surface of the sweet towards its center. This phenomenon, when it is uncontrolled, is known by the name of “turning.” It renders the sweets completely opaque and, usually, white.
Alternatively, the crystallization of boiled sweets can also occur at the center of the candy if it is very high in water or if the storage temperature is very high. Under these conditions, the boiled sweet becomes excessively soft and can no longer be considered a real solid. The boiled sweet becomes more of a liquid supersaturated with crystallizable molecules whose variation toward a crystalline state is unavoidable and practically spontaneous. Specialists designate this type of crystallization by the term “graining”. This phenomenon is particularly observed with sorbitol cast hard candies.
Whiteness in hard-boiled sweets is an important attribute for many applications. Hard-boiled sweets traditionally prepared with sucrose and corn syrup have a tendency to discolor or brown during cooking due to the hydrolysis of the sucrose and/or corn syrup. The use of HSH to prepare hard-boiled sweets, as specified below, was observed to reduce the browning of the boiled sweets. While the inventor does not wish to be bound to any particular theory, it is believed that the use of HSH to prepare boiled sweets prevents the sucrose from reducing. The resulting hard-boiled candy product prepared according to the invention has a higher index of whiteness compared to that of the prior art.
The index of whiteness of the invention and the prior art was measured on the L*a*b* plane using the Gardner's HANDY-COLOR™ Model No. 9200 (BYK-Gardner, Inc., Silver Spring, Md.). The L*a*b* system is shown in FIG. 7. From this Figure, it can be seen that on the L*a*b* plane, +L white, −L black, −a is green, +a is red, +b is yellow, and −b is blue. When using the HANDY-COLOR™ to measure the color of boiled sweets, it is desired to have higher “L” values, which indicates whiteness. Additionally, a lower, or preferably negative “b” values (indicating less yellow or a slight blueish tint) is desired, and a higher, albeit still negative, “a” value (indicating slight greenish tint) is also desired. The browning of sucrose-containing boiled sweets prepared without HSH can be identified by higher, positive “b” values (indicating yellowish tint) and higher, positive “a” values (indicating a red tint).
Sucrose (hereinafter “sugar” or “sucrose”) provides sweetness and humectancy to food products during storage, as well as enhancing flavors and colors. In food applications, sucrose is commonly used in the form of a solution made by dissolving the crystalline materials in water. It is commonly known that sucrose will hydrolyze in solution from low pH to about pH 8.5 and at high temperatures to an equal molar mixture of glucose and fructose, called “invert sugar”. Invert sugar is hygroscopic and is often used as a humectant in many food products such as cream fillings, cakes, soft cookies, and the like. Corn syrups can also be hydrolyzed under similar conditions. Invert sugar produced by the hydrolysis of sucrose causes browning or yellowing of the final product. This can be an unwanted side effect in many applications, notably, hard-boiled candies, where a white color is often preferred.
The aim of the present invention is to overcome the disadvantages of the prior art and to provide a new sucrose-sweetened boiled sweet which satisfies, much better than existing products, the expectations of confectionery manufacturers and the various requirements of practical use, that is to say the boiled sweet can be prepared at atmospheric pressure and exhibits excellent stability and whiteness properties. Existing methods of making sucrose-sweetened boiled sweets from a mixture of sucrose and corn syrups, which use high temperatures, e.g., 160° C. to 180° C., and do not use reduced pressure, i.e., a vacuum, have a tendency to produce finished products that are discolored. Therefore, confectioners would cook the mixture of sucrose and corn syrups at lower temperatures, e.g., from 148° C. to 154° C., and under a vacuum, e.g., 10 to 15 inches of mercury, to avoid the discoloration of the boiled sweet product. The finished boiled sweet would have a relatively high moisture content of 2 to 5 percent, and would be relatively stable. However, there exists a need to prepare sucrose-sweetened boiled sweets that do not discolor and exhibit good stability properties without resorting to the current method of preparation under vacuum. The present invention results in a stable, i.e., reduced hydroscopicity, boiled sweet that is prepared under normal atmospheric pressure and exhibits a high index of whiteness.
Maltodextrins are produced from the hydrolysis of starch. They generally have a dextrose equivalent (DE) between 1 and 20. The DE is a measurement of the reducing power of a starch hydrolysis product expressed as a percentage of the reducing power of the same weight of D-glucose. Although traditionally determined by titration, the DE may be determined by cryoscopy (depression of freezing point). The higher the DE, the lower the number average molecular weight of the product. The maximum possible DE is 100, i.e., pure dextrose. Maltodextrins are usually produced by the action of the enzyme α-amylase on gelatinised starch. Maltodextrin contains a range of nutritive non-sweet polysaccharides with a distribution of molecular weights where the anhydroglucose units are linked predominantly by 1,4 bonds. The commercial product is usually supplied as a free flowing spray-dried powder.
Hydrogenated maltodextrins (HMD) fall within a larger class of sweeteners known as hydrogenated starch hydrolysates (HSH). Hydrogenated starch hydrolysates include hydrogenated glucose syrups, maltitol syrups, and sorbitol syrups, and are a family of products found in a wide variety of foods. They serve a number of functional roles, including use as bulk sweeteners, viscosity or bodying agents, humectants, crystallization modifiers, cryoprotectants and rehydration aids. They also can serve as sugar-free carriers for flavors, colors and enzymes.
Hydrogenated starch hydrolysates are produced by the partial hydrolysis of corn, wheat, or potato starch with the subsequent hydrogenation of the hydrolysate at high temperature under pressure. The end product is an ingredient composed of sorbitol, maltitol, and higher hydrogenated saccharides. By varying the conditions and extent of the hydrolysis, the relative occurrence of various mono-, di-, oligo- and polymeric hydrogenated saccharides in the resulting product can be obtained. Therefore, a wide range of polyols that can satisfy varied requirements with respect to different levels of sweetness, viscosity and humectancy can be produced.
Hydrogenated mono-, di-, oligo- and poly-saccharides arc characterized by the degree of polymerization (DP) after hydrogenation. Hydrogenated monosaccharides have a DP=1. Hydrogenated disaccharides have a DP=2. Hydrogenated tri-, quat-, penta-, hexa-, hepta-, octa-, nona-, and deca-saccharides have DPs of 3, 4, 5, 6, 7, 8, 9, and 10, respectively. Hydrogenated undeca- and greater saccharides have DPs of 11 or greater. The DP may be determined by routine HPLC analysis.
Generally, the term hydrogenated starch hydrolysate can correctly be applied to any polyol produced by the hydrogenation of the saccharide products of starch hydrolysis. In practice, however, certain polyols such as sorbitol, mannitol, and maltitol are referred to by their common chemical names. The term “hydrogenated starch hydrolysate” is more commonly used to describe the broad group of polyols that contain substantial quantities of hydrogenated oligo- and poly-saccharides in addition to any monomeric (such as sorbitol and mannitol) or dimeric (such as maltitol) polyols.
U.S. Pat. No. 5,629,042 to Serpelloni et al., which is hereby incorporated by reference, discloses a sugarless boiled sweet containing a water crystallizable polyol and carbohydrates, e.g., saccharides. The boiled sweet has a water content greater than three percent and a glass transition temperature greater than or equal to 38° C., the glass transition temperature (Tg) being measured at a water content of about 3.2 percent.
U.S. Pat. No. 4,248,945 to Stroz et al., which is hereby incorporated by reference, shows hydrogenated starch hydrolysates having total solids contents of about 72 to 80 weight percent. Based on the dry hydrogenated starch hydrolysates, the total solids contents consist of about 4 to 20 weight percent sorbitol (hydrogenated monosaccharide), 20 to 65 weight percent hydrogenated disaccharides (e.g., maltitol), 15 to 45 weight percent tri- to hepta-hydrogenated oligosaccharides, and 10 to 35 weight percent hydrogenated polysaccharides higher than hepta.
U.S. Pat. No. 4,445,938 to Verwaerde et al., which is hereby incorporated by reference, discloses dry hydrogenated starch hydrolysates consisting of, based on total solids content, less than 14 weight percent of hydrogenated monosaccharides, e.g., sorbitol, less than 35 weight percent of hydrogenated disaccharides, e.g., maltitol, 12 to 18 weight percent of hydrogenated trisaccharides, between 42 and 70 weight percent of hydrogenated quat- to deca-oligosaccharides, and less than 32 weight percent of hydrogenated polysaccharides greater than deca. The Verwaerde composition provides a more stable hydrogenated starch hydrolysate than one which has 15.5 or 30.0 weight percent of hydrogenated quat- to deca-oligosaccharides.
U.S. patent application Ser. No. 09/276,014 by Le (hereinafter “Le”), which is hereby incorporated by reference in its entirety, discloses hydrogenated starch hydrolysates. The HSH prepared according to Le is used in the preparation of the present invention.
When the hydrogenated starch hydrolysate syrups that are presently on the market (e.g., HYSTAR 3375 from Lonza, now SPI Polyols, New Castle, Del. and RA 1000 from Roquette Freres, Lestrem, France) are used to produce hard boiled candies or sweets, the candies or sweets are relatively unstable at high storage temperatures and/or high water contents, which can result in a sticky candy or sweet as explained below. Accordingly, the inventors have surprisingly found that the HSH used in the present invention satisfies a long-felt need by providing a new hydrogenated starch hydrolysate which can be used to prepare hard boiled candies that are stable at high temperatures and high water contents and absorb little moisture in humid conditions.
The inventor has observed that the use of HSH to prepare hard-boiled sweets reduces the hygroscopicity of the boiled sweet, in that the candies produced with HSH do not absorb as much moisture as candies made using only corn syrup and sucrose. FIGS. 1, 2, 3, and 4 show plots of the weight gain of the candy, which evidences the moisture absorption, against the number of days the candy is stored. These plots show that the boiled sweets prepared with HSH absorb significantly less moisture compared to candies prepared using only corn syrup and sucrose. The inventor notes that the reduced moisture absorption does not prevent the surface crystallization of sucrose, but it does reduce the stickiness of the candies. Therefore, the inventor has found that hard candies prepared using HSH as described herein have superior stability properties in terms of reduced moisture absorption, hence, reduced stickiness, when exposed to at 75 percent relative humidity at temperatures from about 25° C. to about 37.8° C.